Remove TraitStore from ty_trait

Use ty_rptr/ty_uniq(ty_trait) rather than TraitStore to represent trait types.
Also addresses (but doesn't close) #12470.
Part of the work towards DST (#12938).

[breaking-change] lifetime parameters in `&mut trait` are now invariant. They used to be contravariant.

src/librustc/metadata/tydecode.rs

@@ -346,10 +346,9 @@ fn parse_ty(st: &mut PState, conv: conv_did) -> ty::t {
         assert_eq!(next(st), '[');
         let def = parse_def(st, NominalType, |x,y| conv(x,y));
         let substs = parse_substs(st, |x,y| conv(x,y));
-        let store = parse_trait_store(st, |x,y| conv(x,y));
         let bounds = parse_bounds(st, |x,y| conv(x,y));
         assert_eq!(next(st), ']');
-        return ty::mk_trait(st.tcx, def, substs, store, bounds.builtin_bounds);
+        return ty::mk_trait(st.tcx, def, substs, bounds.builtin_bounds);
       }
       'p' => {
         let did = parse_def(st, TypeParameter, |x,y| conv(x,y));

src/librustc/metadata/tyencode.rs

@@ -232,12 +232,10 @@ fn enc_sty(w: &mut MemWriter, cx: &ctxt, st: &ty::sty) {
         ty::ty_trait(box ty::TyTrait {
                 def_id,
                 ref substs,
-                store,
                 bounds
             }) => {
             mywrite!(w, "x[{}|", (cx.ds)(def_id));
             enc_substs(w, cx, substs);
-            enc_trait_store(w, cx, store);
             let bounds = ty::ParamBounds {builtin_bounds: bounds,
                                           trait_bounds: Vec::new()};
             enc_bounds(w, cx, &bounds);

src/librustc/middle/kind.rs

@@ -361,9 +361,12 @@ fn check_bounds_on_type_parameters(cx: &mut Context, e: &Expr) {
 fn check_trait_cast(cx: &mut Context, source_ty: ty::t, target_ty: ty::t, span: Span) {
     check_cast_for_escaping_regions(cx, source_ty, target_ty, span);
     match ty::get(target_ty).sty {
-        ty::ty_trait(box ty::TyTrait { bounds, .. }) => {
-            check_trait_cast_bounds(cx, span, source_ty, bounds);
-        }
+        ty::ty_uniq(ty) | ty::ty_rptr(_, ty::mt{ ty, .. }) => match ty::get(ty).sty {
+            ty::ty_trait(box ty::TyTrait { bounds, .. }) => {
+                check_trait_cast_bounds(cx, span, source_ty, bounds);
+            }
+            _ => {}
+        },
         _ => {}
     }
 }
@@ -530,9 +533,8 @@ pub fn check_cast_for_escaping_regions(
 {
     // Determine what type we are casting to; if it is not a trait, then no
     // worries.
-    match ty::get(target_ty).sty {
-        ty::ty_trait(..) => {}
-        _ => { return; }
+    if !ty::type_is_trait(target_ty) {
+        return;
     }
 
     // Collect up the regions that appear in the target type.  We want to

src/librustc/middle/lint.rs

@@ -980,9 +980,6 @@ fn check_heap_type(cx: &Context, span: Span, ty: ty::t) {
                     n_box += 1;
                 }
                 ty::ty_uniq(_) |
-                ty::ty_trait(box ty::TyTrait {
-                    store: ty::UniqTraitStore, ..
-                }) |
                 ty::ty_closure(box ty::ClosureTy {
                     store: ty::UniqTraitStore,
                     ..

src/librustc/middle/mem_categorization.rs

@@ -174,7 +174,6 @@ pub enum deref_kind {
 pub fn opt_deref_kind(t: ty::t) -> Option<deref_kind> {
     match ty::get(t).sty {
         ty::ty_uniq(_) |
-        ty::ty_trait(box ty::TyTrait { store: ty::UniqTraitStore, .. }) |
         ty::ty_closure(box ty::ClosureTy {store: ty::UniqTraitStore, ..}) => {
             Some(deref_ptr(OwnedPtr))
         }
@@ -183,13 +182,6 @@ pub fn opt_deref_kind(t: ty::t) -> Option<deref_kind> {
             let kind = ty::BorrowKind::from_mutbl(mt.mutbl);
             Some(deref_ptr(BorrowedPtr(kind, r)))
         }
-        ty::ty_trait(box ty::TyTrait {
-                store: ty::RegionTraitStore(r, mutbl),
-                ..
-            }) => {
-            let kind = ty::BorrowKind::from_mutbl(mutbl);
-            Some(deref_ptr(BorrowedPtr(kind, r)))
-        }
 
         ty::ty_closure(box ty::ClosureTy {
                 store: ty::RegionTraitStore(r, _),

src/librustc/middle/trans/adt.rs

@@ -292,12 +292,11 @@ impl Case {
     fn find_ptr(&self) -> Option<uint> {
         self.tys.iter().position(|&ty| {
             match ty::get(ty).sty {
-                ty::ty_rptr(_, mt) => match ty::get(mt.ty).sty {
-                    ty::ty_vec(_, None) | ty::ty_str => false,
+                ty::ty_uniq(ty) | ty::ty_rptr(_, ty::mt{ty, ..}) => match ty::get(ty).sty {
+                    ty::ty_vec(_, None) | ty::ty_str| ty::ty_trait(..) => false,
                     _ => true,
                 },
-                ty::ty_uniq(..) | ty::ty_box(..) |
-                ty::ty_bare_fn(..) => true,
+                ty::ty_box(..) | ty::ty_bare_fn(..) => true,
                 // Is that everything?  Would closures or slices qualify?
                 _ => false
             }

src/librustc/middle/trans/base.rs

@@ -1794,6 +1794,9 @@ pub fn get_fn_llvm_attributes(ccx: &CrateContext, fn_ty: ty::t) -> Vec<(uint, u6
         match ty::get(ret_ty).sty {
             // `~` pointer return values never alias because ownership
             // is transferred
+            ty::ty_uniq(it)  if match ty::get(it).sty {
+                ty::ty_str | ty::ty_vec(..) | ty::ty_trait(..) => true, _ => false
+            } => {}
             ty::ty_uniq(_) => {
                 attrs.push((lib::llvm::ReturnIndex as uint, lib::llvm::NoAliasAttribute as u64));
             }
@@ -1803,9 +1806,9 @@ pub fn get_fn_llvm_attributes(ccx: &CrateContext, fn_ty: ty::t) -> Vec<(uint, u6
         // We can also mark the return value as `nonnull` in certain cases
         match ty::get(ret_ty).sty {
             // These are not really pointers but pairs, (pointer, len)
-            ty::ty_rptr(_, ty::mt { ty: it, .. }) |
+            ty::ty_uniq(it) |
             ty::ty_rptr(_, ty::mt { ty: it, .. }) if match ty::get(it).sty {
-                ty::ty_str | ty::ty_vec(..) => true, _ => false
+                ty::ty_str | ty::ty_vec(..) | ty::ty_trait(..) => true, _ => false
             } => {}
             ty::ty_uniq(_) | ty::ty_rptr(_, _) => {
                 attrs.push((lib::llvm::ReturnIndex as uint, lib::llvm::NonNullAttribute as u64));

src/librustc/middle/trans/common.rs

@@ -67,7 +67,7 @@ pub fn type_is_immediate(ccx: &CrateContext, ty: ty::t) -> bool {
         ty::type_is_unique(ty) || ty::type_is_region_ptr(ty) ||
         type_is_newtype_immediate(ccx, ty) || ty::type_is_bot(ty) ||
         ty::type_is_simd(tcx, ty);
-    if simple {
+    if simple && !ty::type_is_trait(ty) {
         return true;
     }
     match ty::get(ty).sty {

src/librustc/middle/trans/consts.rs

@@ -143,7 +143,9 @@ fn const_deref(cx: &CrateContext, v: ValueRef, t: ty::t, explicit: bool)
             let dv = match ty::get(t).sty {
                 ty::ty_ptr(mt) | ty::ty_rptr(_, mt) => {
                     match ty::get(mt.ty).sty {
-                        ty::ty_vec(_, None) | ty::ty_str => cx.sess().bug("unexpected slice"),
+                        ty::ty_vec(_, None) | ty::ty_str | ty::ty_trait(..) => {
+                            cx.sess().bug("unexpected unsized type")
+                        }
                         _ => const_deref_ptr(cx, v),
                     }
                 }

src/librustc/middle/trans/datum.rs

@@ -157,9 +157,7 @@ pub fn appropriate_rvalue_mode(ccx: &CrateContext, ty: ty::t) -> RvalueMode {
      * on whether type is immediate or not.
      */
 
-    if type_is_zero_size(ccx, ty) {
-        ByValue
-    } else if type_is_immediate(ccx, ty) {
+    if type_is_immediate(ccx, ty) {
         ByValue
     } else {
         ByRef

src/librustc/middle/trans/debuginfo.rs

@@ -285,8 +285,8 @@ impl TypeMap {
         // unique ptr (~)       -> {~ :pointee-uid:}
         // @-ptr (@)            -> {@ :pointee-uid:}
         // sized vec ([T, ..x]) -> {[:size:] :element-uid:}
-        // vec slice (&[T])     -> {&<mut> [] :element-uid:}
-        // trait (~ | &[mut] T) -> {:sigil: trait_:svh: / :node-id:_<(:param-uid:),*> }
+        // unsized vec ([T])    -> {[] :element-uid:}
+        // trait (T)            -> {trait_:svh: / :node-id:_<(:param-uid:),*> }
         // closure              -> {<unsafe_> <once_> :store-sigil: |(:param-uid:),* <,_...>| -> \
         //                             :return-type-uid: : (:bounds:)*}
         // function             -> {<unsafe_> <abi_> fn( (:param-uid:)* <,_...> ) -> \
@@ -361,18 +361,12 @@ impl TypeMap {
                 let inner_type_id = self.get_unique_type_id_as_string(inner_type_id);
                 unique_type_id.push_str(inner_type_id.as_slice());
             },
-            ty::ty_vec(ty::mt { ty: inner_type, mutbl }, optional_length) => {
+            ty::ty_vec(ty::mt { ty: inner_type, .. }, optional_length) => {
                 match optional_length {
                     Some(len) => {
                         unique_type_id.push_str(format!("[{}]", len).as_slice());
                     }
                     None => {
-                        unique_type_id.push_char('&');
-
-                        if mutbl == ast::MutMutable {
-                           unique_type_id.push_str("mut");
-                        }
-
                         unique_type_id.push_str("[]");
                     }
                 };
@@ -382,12 +376,6 @@ impl TypeMap {
                 unique_type_id.push_str(inner_type_id.as_slice());
             },
             ty::ty_trait(ref trait_data) => {
-                match trait_data.store {
-                    ty::UniqTraitStore => unique_type_id.push_char('~'),
-                    ty::RegionTraitStore(_, ast::MutMutable) => unique_type_id.push_str("&mut"),
-                    ty::RegionTraitStore(_, ast::MutImmutable) => unique_type_id.push_char('&'),
-                };
-
                 unique_type_id.push_str("trait ");
 
                 from_def_id_and_substs(self,
@@ -2901,6 +2889,16 @@ fn type_metadata(cx: &CrateContext,
                     let i8_t = ty::mk_i8();
                     heap_vec_metadata(cx, pointee_type, i8_t, unique_type_id, usage_site_span)
                 }
+                ty::ty_trait(box ty::TyTrait {
+                        def_id,
+                        ref substs,
+                        ref bounds
+                    }) => {
+                    MetadataCreationResult::new(
+                        trait_metadata(cx, def_id, t, substs, ty::UniqTraitStore,
+                                       bounds, unique_type_id),
+                    false)
+                }
                 _ => {
                     let pointee_metadata = type_metadata(cx, pointee_type, usage_site_span);
                     return_if_created_in_meantime!();
@@ -2917,6 +2915,17 @@ fn type_metadata(cx: &CrateContext,
                 ty::ty_str => {
                     vec_slice_metadata(cx, t, ty::mk_i8(), unique_type_id, usage_site_span)
                 }
+                ty::ty_trait(box ty::TyTrait {
+                        def_id,
+                        ref substs,
+                        ref bounds
+                    }) => {
+                    MetadataCreationResult::new(
+                        trait_metadata(cx, def_id, t, substs,
+                                       ty::RegionTraitStore(ty::ReStatic, mt.mutbl),
+                                       bounds, unique_type_id),
+                    false)
+                }
                 _ => {
                     let pointee = type_metadata(cx, mt.ty, usage_site_span);
                     return_if_created_in_meantime!();
@@ -2930,16 +2939,6 @@ fn type_metadata(cx: &CrateContext,
         ty::ty_closure(ref closurety) => {
             subroutine_type_metadata(cx, unique_type_id, &closurety.sig, usage_site_span)
         }
-        ty::ty_trait(box ty::TyTrait {
-                def_id,
-                ref substs,
-                store,
-                ref bounds
-            }) => {
-            MetadataCreationResult::new(
-                trait_metadata(cx, def_id, t, substs, store, bounds, unique_type_id),
-                false)
-        }
         ty::ty_struct(def_id, ref substs) => {
             prepare_struct_metadata(cx,
                                     t,

src/librustc/middle/trans/expr.rs

@@ -769,15 +769,12 @@ fn trans_rvalue_dps_unadjusted<'a>(bcx: &'a Block<'a>,
         }
         ast::ExprCast(ref val, _) => {
             // DPS output mode means this is a trait cast:
-            match ty::get(node_id_type(bcx, expr.id)).sty {
-                ty::ty_trait(..) => {
-                    let datum = unpack_datum!(bcx, trans(bcx, &**val));
-                    meth::trans_trait_cast(bcx, datum, expr.id, dest)
-                }
-                _ => {
-                    bcx.tcx().sess.span_bug(expr.span,
-                                            "expr_cast of non-trait");
-                }
+            if ty::type_is_trait(node_id_type(bcx, expr.id)) {
+                let datum = unpack_datum!(bcx, trans(bcx, &**val));
+                meth::trans_trait_cast(bcx, datum, expr.id, dest)
+            } else {
+                bcx.tcx().sess.span_bug(expr.span,
+                                        "expr_cast of non-trait");
             }
         }
         ast::ExprAssignOp(op, ref dst, ref src) => {
@@ -1578,7 +1575,7 @@ pub fn cast_type_kind(t: ty::t) -> cast_kind {
         ty::ty_float(..)   => cast_float,
         ty::ty_ptr(..)     => cast_pointer,
         ty::ty_rptr(_, mt) => match ty::get(mt.ty).sty{
-            ty::ty_vec(_, None) | ty::ty_str => cast_other,
+            ty::ty_vec(_, None) | ty::ty_str | ty::ty_trait(..) => cast_other,
             _ => cast_pointer,
         },
         ty::ty_bare_fn(..) => cast_pointer,
@@ -1794,8 +1791,8 @@ fn deref_once<'a>(bcx: &'a Block<'a>,
     let r = match ty::get(datum.ty).sty {
         ty::ty_uniq(content_ty) => {
             match ty::get(content_ty).sty {
-                ty::ty_vec(_, None) | ty::ty_str
-                    => bcx.tcx().sess.span_bug(expr.span, "unexpected ~[T]"),
+                ty::ty_vec(_, None) | ty::ty_str | ty::ty_trait(..)
+                    => bcx.tcx().sess.span_bug(expr.span, "unexpected unsized box"),
                 _ => deref_owned_pointer(bcx, expr, datum, content_ty),
             }
         }
@@ -1812,8 +1809,8 @@ fn deref_once<'a>(bcx: &'a Block<'a>,
         ty::ty_ptr(ty::mt { ty: content_ty, .. }) |
         ty::ty_rptr(_, ty::mt { ty: content_ty, .. }) => {
             match ty::get(content_ty).sty {
-                ty::ty_vec(_, None) | ty::ty_str
-                    => bcx.tcx().sess.span_bug(expr.span, "unexpected &[T]"),
+                ty::ty_vec(_, None) | ty::ty_str | ty::ty_trait(..)
+                    => bcx.tcx().sess.span_bug(expr.span, "unexpected unsized reference"),
                 _ => {
                     assert!(!ty::type_needs_drop(bcx.tcx(), datum.ty));
 

src/librustc/middle/trans/glue.rs

@@ -100,7 +100,7 @@ pub fn get_drop_glue_type(ccx: &CrateContext, t: ty::t) -> ty::t {
 
         ty::ty_uniq(typ) if !ty::type_needs_drop(tcx, typ) => {
             match ty::get(typ).sty {
-                ty::ty_vec(_, None) | ty::ty_str => t,
+                ty::ty_vec(_, None) | ty::ty_str | ty::ty_trait(..) => t,
                 _ => {
                     let llty = sizing_type_of(ccx, typ);
                     // `Box<ZeroSizeType>` does not allocate.
@@ -295,25 +295,42 @@ fn make_drop_glue<'a>(bcx: &'a Block<'a>, v0: ValueRef, t: ty::t) -> &'a Block<'
             decr_refcnt_maybe_free(bcx, v0, body_ty)
         }
         ty::ty_uniq(content_ty) => {
-            let llbox = Load(bcx, v0);
-            let not_null = IsNotNull(bcx, llbox);
             match ty::get(content_ty).sty {
                 ty::ty_vec(mt, None) => {
+                    let llbox = Load(bcx, v0);
+                    let not_null = IsNotNull(bcx, llbox);
                     with_cond(bcx, not_null, |bcx| {
                         let bcx = tvec::make_drop_glue_unboxed(bcx, llbox, mt.ty);
                         // FIXME: #13994: the old `Box<[T]>` will not support sized deallocation
                         trans_exchange_free(bcx, llbox, 0, 8)
                     })
                 }
                 ty::ty_str => {
+                    let llbox = Load(bcx, v0);
+                    let not_null = IsNotNull(bcx, llbox);
                     with_cond(bcx, not_null, |bcx| {
                         let unit_ty = ty::sequence_element_type(bcx.tcx(), t);
                         let bcx = tvec::make_drop_glue_unboxed(bcx, llbox, unit_ty);
                         // FIXME: #13994: the old `Box<str>` will not support sized deallocation
                         trans_exchange_free(bcx, llbox, 0, 8)
                     })
                 }
+                ty::ty_trait(..) => {
+                    let lluniquevalue = GEPi(bcx, v0, [0, abi::trt_field_box]);
+                    // Only drop the value when it is non-null
+                    with_cond(bcx, IsNotNull(bcx, Load(bcx, lluniquevalue)), |bcx| {
+                        let dtor_ptr = Load(bcx, GEPi(bcx, v0, [0, abi::trt_field_vtable]));
+                        let dtor = Load(bcx, dtor_ptr);
+                        Call(bcx,
+                             dtor,
+                             [PointerCast(bcx, lluniquevalue, Type::i8p(bcx.ccx()))],
+                             []);
+                        bcx
+                    })
+                }
                 _ => {
+                    let llbox = Load(bcx, v0);
+                    let not_null = IsNotNull(bcx, llbox);
                     with_cond(bcx, not_null, |bcx| {
                         let bcx = drop_ty(bcx, llbox, content_ty);
                         trans_exchange_free_ty(bcx, llbox, content_ty)
@@ -336,16 +353,6 @@ fn make_drop_glue<'a>(bcx: &'a Block<'a>, v0: ValueRef, t: ty::t) -> &'a Block<'
                 }
             }
         }
-        ty::ty_trait(box ty::TyTrait { store: ty::UniqTraitStore, .. }) => {
-            let lluniquevalue = GEPi(bcx, v0, [0, abi::trt_field_box]);
-            // Only drop the value when it is non-null
-            with_cond(bcx, IsNotNull(bcx, Load(bcx, lluniquevalue)), |bcx| {
-                let dtor_ptr = Load(bcx, GEPi(bcx, v0, [0, abi::trt_field_vtable]));
-                let dtor = Load(bcx, dtor_ptr);
-                Call(bcx, dtor, [PointerCast(bcx, lluniquevalue, Type::i8p(bcx.ccx()))], []);
-                bcx
-            })
-        }
         ty::ty_closure(ref f) if f.store == ty::UniqTraitStore => {
             let box_cell_v = GEPi(bcx, v0, [0u, abi::fn_field_box]);
             let env = Load(bcx, box_cell_v);